A variety of available blood processing systems allows for the collection and processing of particular blood components, rather than whole blood, from donors or patients. In the case of a blood donor, whole blood is drawn from the donor, a desired blood constituent separated and collected, and the remaining blood components returned to the donor. By removing only particular constituents rather than whole blood, it takes the donor's body a shorter time period to recover to normal blood levels, thereby increasing the frequency with which the donor may donate blood. It is beneficial to increase in this manner the overall supply of blood constituents made available for health care, such as red blood cells (RBCs), leukocytes, mononuclear cells (MNCs), plasma, and/or platelets, etc. In the case of a patient, whole blood is similarly drawn from the patient, a particular blood constituent first separated and then collected and/or treated, and the remaining blood components returned to the patient. The collected and/or treated blood constituent may be saved for future use, returned to the patient, and/or discarded and replaced with a suitable replacement.
The separation of blood components from whole blood typically takes place prior to the collection or treatment of the separated blood component and may be achieved through a spinning membrane or centrifugation, in which whole blood is passed through a centrifuge or membrane after it is withdrawn from the patient/donor. To avoid contamination and possible infection of the patient/donor, the blood is preferably contained within a sealed, sterile fluid flow system during the entire separation process. Typical blood processing systems thus may include a permanent, reusable hardware assembly containing the hardware (drive system, pumps, valve actuators, programmable controller, and the like) that pumps the blood, and a disposable, sealed and sterile fluid circuit that is mounted in cooperation on the hardware. In the case of separation via centrifugation, the hardware assembly includes a centrifuge that may engage and spin a separation chamber of the disposable fluid circuit during a blood separation step. The blood, however, may make actual contact only with the fluid circuit, which assembly may be used only once and then discarded or used for other purposes. In the case of separation via a spinning membrane, a disposable single-use spinning membrane may be used in cooperation with the hardware assembly and disposable fluid circuit.
In the case of separation via centrifugation, as the whole blood is spun by the centrifuge, the heavier (greater specific gravity) components, such as red blood cells, move radially outwardly away from the center of rotation toward the outer or “high-G” wall of the separation chamber of the fluid circuit. The lighter (lower specific gravity) components, such as plasma, migrate toward the inner or “low-G” wall of the separation chamber. Various ones of these components can be selectively removed from the whole blood by forming appropriately located channeling seals and outlet ports in the separation chamber of the fluid circuit.
In the case of separation via a spinning membrane, whole blood may be processed within a disposable spinning membrane, rather than within a separation chamber of a fluid circuit. Larger molecules, such as red blood cells, may be retained within one side of the membrane, while the smaller molecules, such as plasma, may escape through the pores of the membrane to the other side of the membrane. Various ones of these components can be selectively removed from the whole blood by forming appropriately located outlet ports in the housing of the membrane column. Various types of membranes with different pore sizes may be used, depending on the components to be separated.
In the case of MNC collection, which includes the collection of lymphocytes, monocytes, and/or stem cells, MNCs can be removed from the whole blood of a patient/donor, collected, and/or subjected to various therapies. Collected and treated MNCs may then be returned to the patient/donor for the treatment of various blood diseases by, e.g., eliminating immunogenicity in cells, inactivating or killing selected cells, inactivating viruses or bacteria, reconstituting the immune system, and/or activating desirable immune responses. MNC treatments are used for blood or solid organ/tissue cancers, photopheresis treatments, autologous and allogeneic stem cell transplants, donor lymphocyte infusions, research collections, etc.